"greylisting"

[David Nicol]

http://www.greylisting.org/


the idea is, reject any unseen source the first time it is seen, for an hour
or two.  This cuts down on bot-sent messages at the small price of
delaying (!!! not requiring a full c/r) the first message from a new RAPNAP.

this would be a completely trivial plug-in.  Something like

    tie %greylistdb, BerkeleyDB => ...
    ...
    if (!exists $greylistdb{$EnevelopeReturnAddress, $PeerNetworkAddress}){
        $greylistdb{$EnevelopeReturnAddress, $PeerNetworkAddress} = time;
        SOFTFAIL4XX
    }
    if ($greylistdb{$EnevelopeReturnAddress, $PeerNetworkAddress} <
time + 3600){
        passed the check
    }
    SOFTFAIL4XX

makes sense for listservs, does not make sense for VERP recipients, at least
not without a way to skip the check from known-good sources.

  


-- 
David L Nicol
Communication is neither obvious nor inscrutable.